Permutation

chli
MemberChestbursterOctober 11, 2017We’ve had a lot of discussions about surviving engineers, engineer babies, reviving of dead engineers and what have you.
My personal opinion is that these hypotheses are the product of the imagination of the artists who made David’s sketches (not necessarily part of the storyline or Scott’s intentions). The sketches are supposed to be looked at from a distance, giving an idea of David’s endeavours.
If you listen to Scott’s audio commentary to AC, we get the information that creatures seen in David’s lab are “permutations” and the result of a lack of human DNA.
If David had access to (living) engineers, the result would probably have been even more hideous than the xeno-like creature erupting from Oram's (and Lopé's) ribcage, perhaps what we get a glimpse of in the mural . . .
But, David lacks human DNA (engineer DNA are sufficiently close since they are humanoids) and so The Covenant crew is needed (and most welcome). Oram and Lopé are the unfortunate guys who contribute with human DNA (which is what the facehugger needs - a suitable host for the gestation of its embryo).
So David dabbles in creation using the pathogen, crossbreeding and hybridization with eggs from Shaw, flora, and what's left of the fauna (mostly insects) on Planet 4. But he can't get any further without suitable DNA from humanoids . . .